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Username Post: 409 block codes        (Topic#366484)
"4th Year Gold Supporting Member
Posts: 285
Age: 69
Loc: Asheville, NC
Reg: 07-22-17
09-22-21 12:10 PM - Post#2827702    

The left rear block #3857656 dates it 64-65. The right rear # is 166 or I66. Did they use julian dates then which would make the 166 June 15th or is the I66 still missing a number?


1965 Impala SS


Posts: 671
Loc: Montreal,Qc
Reg: 06-01-16
09-26-21 09:29 AM - Post#2827990    
    In response to 6T5

most probably it's #166, I66 , the last number would be #5 for 1965 not #6 ,would mean 1966, if any 409 in 1966 (not) ?

My first car: 1970 Olds, 442,455 (1981-82)
My last car : 1966 Chev. Impala convertible,396 (1984-2020)
current car: Can't afford them anymore ...

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Age: 61
Loc: Grande Prairie AB & N...
Reg: 09-22-14
09-26-21 11:02 AM - Post#2827994    
    In response to space66

For block date codes "I" is September which would have to be 1964 for that block part number because the 409 was replaced in February 1965.
Oshawa had the 409 available through the whole 1965 production year since the 396 was not available to that plant, but I don't think McKinnon cast 409's.
My 283 is a McKinnon cast block though.
The only way that could be a September 6th 1966 casting is if service blocks were still being produced.
No idea if that was done or not.


65 Impala SS Evening Orchid convertible 283 2V with Powerglide and 10 bolt 3.08 open by PO, originally 3.36
Build date Dec. 21 '64 Oshawa

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Posts: 1215
Loc: Hebron, ME
Reg: 11-17-04
10-09-21 07:44 AM - Post#2828859    
    In response to Oshawa65SS

166 would be the Julian date code. Would make it a very early 65 model year block


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